1. Field of the Invention
This invention relates to tube couplings and in particular to couplings utilising a collet arrangement in a coupling body to receive and lock a tube in place automatically when a tube is inserted in the body.
2. Background Prior Art
Examples of such couplings are described and illustrated in U.K. Patent Publications Nos. 1,520,742, 1,573,757 and 2,131,903. In certain applications it is desirable to provide a secondary holding arrangement for a tube should the primary collet arrangement fail to grip the tube for any reason and such an arrangement may make use of an up-set formed on the tube adjacent its end. Our European Patent Application No. 93309027.6 shows certain arrangements for achieving this. The object of this invention is to simplify and improve further the provision of a dual locking for the tube in a coupling body.